This invention relates generally to means and method for accomplishing the separation of particulate matter such as dust from industrial gases and, more specifically, it pertains to collecting particulate matter from a gas flow through the use of a contacting chamber wherein the gas flow is subjected to a continuing flow of water.
Apparatus has been previously disclosed for cleaning industrial gases and collecting particulate matter therefrom wherein the particle-laden gas flow is centrifugally whirled through a contacting chamber through a dense flow of water droplets directed across or against the flow direction of the gas being cleaned.
A typical example of such apparatus includes a vertically elongated contacting chamber wherein the gas flow is directed to the chamber through an inlet transverse to the axis of the chamber and tangentially oriented such that the gas moves upwardly through the chamber in a spiral pathway toward an outlet tube thereabove. Water is directed downwardly through the contacting chamber generally from the upper end thereof and the process of separating particulate matter from the gas flow takes place substantially in the portion of the chamber adjacent the tangential gas inlet. Here a curtain of water droplets is established and the particulate matter is collected on the surface of the water droplets.
The particles of matter and the water droplets are continuously driven by centrifugal force against the inside chamber surface where both tend to collect and form a water layer or sheet containing captured particles therein. This particle-laden layer, now spearated from the gas flow, progresses downwardly toward the discharge opening.
It is well known that in a given contacting chamber of fixed diameter the increase of the velocity of the gas flow in the tangential inlet causes a corresponding increase in the centrifugal force of the gas flow moving upwardly through the chamber. It has been determined that the effectiveness of the centrifugal force and the water curtain and the water droplets thereof within the chamber will increase as a function of increased gas flow velocity through the tangential inlet. Although the efficiency of such apparatus can be enchanced by increasing the velocity of the gas flow coming into the chamber, such increase in velocity for a substantially unchanging gas flow rate has a detrimental effect on the downwardly directed water flow along the inside surface of the chamber. The increased velocity generates a turbulence upon the water flow moving downwardly on the inside surface of the chamber and an increased upward traction, preventing the desired comparatively smooth descending water flow pattern. Instead, the water is held back and accumulated in the general area of the chamber above the tangential gas inlet such that the downward water flow becomes intermittent. The water in this part of the chamber must then accumulate to form a certain mass whereby it will overcome the force of the rising gas flow before continuing its downward movement. This reaction to the water flow in response to the increased gas flow velocity results in unpredictable fluctuations in pressure within the chamber and in a reduction of separation efficiency. Such a reaction can also cause objectionable vibrations of the entire apparatus.